<span>the error of assuming that what is true of a member of a group is true for the group as a whole.so letter b may be a good choice</span>
Formula of circle:
C= 2πr
The radius is half of the diameter, so divide 9 by 2
18/2=9
Then plug in 9 as the radius in the formula.
C= 2π(9)
Using you calculator multiply 2 by the symbol "π" and 9
Exact Form is 18π
Decimal Form is 56.54866776...